Commander Keen in Invasion of the Vorticons

Commander Keen in Invasion of the Vorticons
Title screen from "Marooned on Mars"
Developer(s)	Ideas from the Deep
Publisher(s)	Apogee Software
Designer(s)	Tom Hall
Programmer(s)	John Carmack John Romero
Artist(s)	Adrian Carmack
Series	Commander Keen
Platform(s)	MS-DOS
Release date(s)	December 14, 1990
Genre(s)	Side-scrolling platformer
Mode(s)	Single-player

Commander Keen in Invasion of the Vorticons is a three-part episodic side-scrolling platform video game developed by Ideas from the Deep (a precursor to id Software) and published by Apogee Software in 1990 for MS-DOS. It is the first set of episodes of the Commander Keen series. The game follows the titular Commander Keen, an eight-year-old child genius, as he retrieves the stolen parts of his spaceship from the cities of Mars, prevents an alien mothership that arrived while he was delayed from destroying landmarks on Earth, and hunts down the leader of the aliens, the Grand Intellect, on the alien home planet. The three episodes feature Keen running, jumping, and shooting through various levels while opposed by aliens, robots, and other hazards.

In September 1990, John Carmack, while working at programming studio Softdisk, developed a way to implement side-scrolling video games on personal computers (PCs), which at the time was the province of dedicated home video game consoles. After a demo of a PC version of Super Mario Bros. 3 developed by Carmack and his coworkers John Romero and Tom Hall, along with Jay Wilbur and Lane Roathe, failed to convince Nintendo to invest in a PC port of their game, they were approached by Scott Miller of Apogee Software to develop an original game to be published through the Apogee shareware model. Hall designed the three-part game, Carmack and Romero programmed it, Wilbur managed the team, and artist Adrian Carmack helped later in development. The team worked continuously for almost three months on the game, working late into the night at the office at Softdisk and taking their work computers to John Carmack's home to continue developing the game.